Translucent gasket comprising a watermark that is not visible in reflected light

ABSTRACT

The invention relates to a light-transmitting gasket intended to be positioned on the base of a stopper or cap, in the form of a support having a light-transmitting coating applied to at least one of the surfaces thereof. The gasket is characterised in that the coating contains a watermark, i.e. an image visible in transmitted light, but not visible in reflected light.

The subject of the invention is a novel gasket whose essentialcharacteristic is to be provided with a watermark.

In the remainder of the description and in the claims, the term“watermark” denotes a drawing or an image that is observable or visiblein transmitted light. By “observable or visible in transmitted light” ismeant an element (here the watermark) that it is visible, in particularwith the naked eye, when placed between the eye of the observer and alight source, so that the eye perceives the rays of the light sourcethrough the observed element. In practice, the watermark is visible bytransparency in visible light, that is to say at a wavelength between380 and 780 nm.

The watermarks are visible in transmitted light, but they are notvisible in reflection, i.e. when the eye of the observer and the lightsource are placed on the same side of the element to be observed, sothat the eye perceives the rays of the light source reflecting on theobserved element.

The seal of the invention is of the type used for the sealing ofconsumer products, in particular in the food or cosmetic industry.

These include notably a one-piece gasket. In a known manner, theone-piece gasket consists of a foamed or non-foamed support. In the caseof foam, they are foams of polypropylene (PP), polyethylene (PE) orpolyethylene terephthalate (PET), optionally laminated with PP, PE orpolyethylene terephthalate (PET). The purpose of these seals is toensure the sealing of the packages against, first of all, the content,liquid or not, but also against the oxygen, as well as against aromasand odors.

These seals are usually delivered to the stopper or cap manufacturer.The manufacturer inserts them at the bottom of a stopper or a cap anddelivers them to the final customer. The final customer fills thecontainers (flacon, bottle, pot . . . ) and then closes them by means ofthe stopper or the cap provided with its joint.

The invention also relates to the double-piece joints intended to beglued or sealed on the container lip. These seals consist of two parts,respectively a lid and a support. The lid is placed over the entireperiphery of the upper rim of the finish of the container or a lip, thusisolating the container from the outside. The support is generallythicker. It is inserted, without being fixed, at the bottom of the cap.Prior to the first opening of the container, the support and the lid maybe secured by means of a temporary adhesive. We can distinguishdouble-piece joints that are glued or heat-sealed.

With regard to the glued double-piece, the bonding is conventionallycarried out by means of glue compatible with the lip and the undersideof the lid.

When the seal is intended to be sealed on the container, it has asealing layer applied on its underside. Sealing is performed byinduction heat sealing through the cap. This heat sealing is madepossible by the combined action of a conductive material inserted intothe thickness, preferably of the cap, which, as an effect of themagnetic induction, heats, causing the melting of the sealing film onthe lip.

The distribution channel of these joints is identical to thatfunctioning and described previously for one-piece gaskets.

Numerous solutions have been proposed to make it possible to verify thatthe product purchased by the consumer was an original product and/or hadnever been opened.

As an example, in the field of wine stoppers, document US2003/0127846describes an anti-counterfeiting device in the form of sealing stripinner face of which is covered by an image appearing only on contactwith oxygen. As the strip is removed, the image, in particular the brandof the beverage, is revealed in contact with the oxygen.

Document US Pat. No. 2014/0224800 describes a double-piece gasket of thelift n peel® type, where one of the layers of the lid is covered with ahologram. The hologram appears when the lid is removed, which guaranteesthe origin of the product. Moreover, the application of the hologramover the entire surface of the layer, including on the part secured tothe lip, means that the membrane cannot be put back once separated.Therefore, the described seal makes it possible to guarantee theinviolability of the product.

For manufacturers of cosmetic and food products it is essential toguarantee the consumer the origin of the products and theirinviolability. From the manufacturer's point of view, it is alsoessential that the seal supplied to him comes from the original jointmanufacturer. Since most of the time the joints are not delivered to themanufacturer of the final product directly by the joint manufacturer butby an intermediary manufacturer of the stopper, there is a risk that thejoint that is inserted in the stopper is not the original one. Takinginto account the specificity of the joints as an oxygen, aroma, odorbarrier, depending on the nature of the product to be protected, it iseasy to imagine the consequences of inserting a joint not responding tothe specific requirements.

The necessary solution is the marking of the joint to represent thejoint manufacturer. The constraint for the consumer product manufactureris that he does not wish that this marking be visible to the finalconsumer. This is not desirable, apart from the aesthetic aspect thatcould be affected.

Document U.S. Pat. No. 3,628,271 describes a stopper outer surface ofwhich is covered with a layer revealing an expiration date under UVlight.

Document U.S. Pat. No. 7,789,074 describes a gasket consisting of acompressible layer on which a transparent film is applied. Thecompressible layer is structured. It is in the form of a series ofextruded filaments. The structure of the compressible layer is visiblein reflection whatever the side of the joint so that it is not awatermark.

The problem which the invention proposes to solve is to develop a gasketprovided with an identification means that is not visible to theconsumer.

To do this end, the Applicant had the idea to integrate a watermark intothe thickness of the gasket.

More precisely, the subject of the invention is a light transmittinggasket, in practice visible light, intended in particular to be insertedat the bottom of a cap or a stopper in the form of a supporttransmitting itself the light and advantageously made of a foamedmaterial on at least one of the faces on which is applied a material,referred to in the remainder of the description and in the claims by theterm “coating” and also transmitting the light.

This gasket is characterized in that the face of the support on whichthe coating is applied, and more precisely the coating itself, has awatermark, that is to say an image visible in transmitted light and notvisible in reflection.

According to the invention, the gasket of the invention is a one-piecegasket or the support part of a double-piece gasket.

In the case of a one-piece gasket, whether it is the stopper or capmanufacturer or the manufacturer of the final product, who receives thestopper+seal assembly or, more rarely, the seal directly, all of themcan perfectly identify the origin of the gasket. In the case of adouble-piece seal, the identification of the joint, in practice of itssupport, can only be carried out after the support has been separatedfrom the lid.

In fact it is sufficient to place the gasket between the eye and a lightsource to detect the watermark pattern. The term “drawing” of coursecovers any type of marking, whether it is a logo, a name, a drawing, animage, a pattern, etc.

As already mentioned, the verification can be done directly when thejoint is a one-piece gasket. In the case of a two-piece gasket,verification can be carried out after separation of the support and thesealing cap or without prior separation if the seal is not completelyopaque.

According to a first embodiment, the material constituting the supportis an foamed material that is preferably chosen from the groupcomprising low density polyethylene (PE), polypropylene (PP), PET,polystyrene (PS). In practice, the density of the foam is between 30 and500 kg/m³, advantageously between 150 and 400 kg/m³, that is to say anaverage density.

According to another characteristic, the thickness of the foam isadvantageously between 1 and 3 mm.

According to a second embodiment, the material constituting the supportis a non-foamed material which is preferably chosen from the groupcomprising polyethylene, polyethylene copolymers, thermoplasticelastomers, PP, PET, PS. In practice, the density of the support is inthis case between 800 and 1500 kg/m³.

In the two previous embodiments, the support is extruded, in view of thenature of the materials used.

In another embodiment, the support is made of a non-foamed, non-extrudedand light-transparent material. It may be, for example, cardboard with adensity advantageously between 40 and 600 kg/m³.

According to the invention, the light-transmitting coating applied tothe support comprises a paper sheet and/or at least one polymer film.

In a preferred embodiment, the light transmitting coating comprises atleast one polymeric film.

In practice, the polymeric film is chosen from the group comprising PET,PVDC, PP, polyester, PA (polyamide), PE (polyethylene). The filmpreferably has a thickness between 5 and 100 micrometers.

In one particular embodiment, the light transmitting coating comprisestwo polymer films.

They can be two coextruded films or two films associated by means of anadhesive. In a particular embodiment, the light transmitting material isa complex consisting of a polyester top film and a polyethylene bottomfilm.

The two films once associated are then calendared or laminated onto thesupport.

The light transmitting coating is applied to one or both sides of thesupport that can be extruded or not. When the support, extruded or not,is covered only on one side, the watermark is applied to the facecomprising the light-transmitting coating.

The seal can be positioned at the bottom of the stopper or cap in anydirection.

Of course, the shape of the joints of the invention will be determinedas a function of the shape of the stopper or of the cap.

According to an essential characteristic, the light transmitting coatinghas a watermark. This watermark can be obtained in various ways,recalling that, by definition, it is a pattern visible in passing light.

In a preferred embodiment, the light transmitting coating is white incolor and the foamed or non-foamed material is advantageously also whitein color. At the same time, the watermark is in the form of a whiteprint and is preferably applied to the back of the light transmittingcoating. In this case, the coating is advantageously a polymer film.

Finally and according to another feature, the watermark is appliedbetween the support and the light-transmitting coating, in particularthe film. As already stated, the watermark, that is to say an imagevisible in passing light and not visible in reflection, is preferablyapplied to the back of the light-transmitting coating.

The invention and the advantages thereof will become apparent from thedescription which follows.

A repeated pattern of white color is printed on a strip of white PETpolymer film. The PET film has a thickness of 25 microns.

This strip of film is laminated on a white foamed PE strip. The foam hasa thickness of 1 mm and a density of 200 kg/m3.

The gaskets of the desired size are cut out in the thickness of thecomplex obtained.

If the gasket is placed between the eye and a light source, thewatermark is visible between the support and the light transmittingmaterial.

The invention and the advantages which result therefrom are wellapparent from the foregoing description. In particular, it is possibleto guarantee the manufacturers of consumer products the origin of thegaskets used in the packaging.

1. A light-transmitting gasket intended in particular to be inserted atthe bottom of a stopper or cap, in the form of a support on at least oneof the faces of which a light-transmitting coating is applied,characterized in that the coating contains a watermark, that is to sayan image visible in transmitted light and not visible in reflection. 2.The gasket according to claim 1, characterized in that thelight-transmitting coating comprises a paper sheet and/or at least onepolymeric film.
 3. The gasket according to claim 1, characterized inthat the support is made of a foamed material and is advantageouslychosen from the group comprising low density polyethylene (PE),polypropylene (PP), PET, and polystyrene (PS).
 4. The gasket accordingto claim 3, characterized in that a density of the foamed material isbetween 30 and 500 kg/m³.
 5. The gasket according to claim 3,characterized in that thickness of the foamed material is between 1 and3 mm.
 6. The gasket according to claim 1, characterized in that thesupport is made of a non-foamed material and is advantageously chosenfrom the group comprising polyethylene, polyethylene copolymers,thermoplastic elastomers, PP, PET, and PS.
 7. The gasket according toclaim 6, characterized in that the material has a density between 800and 1500 kg/m³.
 8. The gasket according to claim 1, characterized inthat the support is made of a non-foamed, non-extruded material.
 9. Thegasket according to claim 8, characterized in that the paper has adensity between 40 and 600 kg/m³.
 10. The gasket according to claim 2,characterized in that the polymer film is selected from the groupcomprising PET, PVDC, polyester, PP, PA, and PE.
 11. The gasketaccording to claim 2, characterized in that the polymeric film is whitein color.
 12. The gasket according to claim 2, characterized in that thewatermark is in the form of a white-colored printing.
 13. The gasketaccording to claim 1, characterized in that the watermark is in the formof a printing applied between the support and the light-transmittingcoating.
 14. The gasket according to claim 1, characterized in that thewatermark is applied to the back of the light-transmitting coating. 15.The gasket according to claim 8, wherein the material comprises paper.